Dr. Jason McClure - Chief Scientist at Princeton Instruments
A Brief Interview with
Inventor of the IsoPlane
Q: Was the development of the IsoPlane motivated by your own
frustration with inferior imaging spectrographs?
A: We at Princeton Instruments had been searching for methods
to improve the imaging performance of the Czerny-Turner
spectrograph for several years. It was only after reading
a book on the aberration theory of the reflecting telescope
that I happened upon the idea of the IsoPlane. I was truly
motivated by the elegant treatment of image aberration in
the Schmidt-Cassegrain telescope through the use of Seidel
aberration theory. From this theory and some creativity, the
IsoPlane SCT-320 was developed. It is named the Schmidt-
Czerny-Turner (SCT) from the Schmidt-like corrector the
instrument uses to help achieve its imaging performance.
Q: Do you think that spectroscopists had generally
accepted that this type of spectrograph would
never be invented?
A: I believe so. The commercial imaging Czerny-
Turner spectrograph is roughly 30 years old and
has seen little to no improvement in that time. I
think many spectroscopists simply believed the
design was fully mature and that no further
discoveries were possible.
Q: Why has it taken so long for this product
to be developed?
A: Seidel aberration theory is over 150 years old,
and the Czerny-Turner spectrograph is about
80 years old. I think the reason the IsoPlane
took so long to be developed was because
we were all looking in the wrong place for the
answers. Astronomers have hundreds more years’
experience than spectroscopists, and have fully
developed Seidel aberration theory to describe
every variant of the telescope. Such history does
not exist for the spectrograph. We are proud to
play a role in creating history with the discovery of